Research On Indoor Comfort Of Small Temperature Difference End And Fresh Air Compound Air Conditioning System

In areas with cold winter and hot summer,air-conditioning systems for heating in winter and cooling in summer mostly adopt traditional air-conditioning system modes,which not only have high energy consumption but also poor comfort.The temperature and humidity independent control air-conditioning system has attracted people’s attention as a new type of comfortable air-conditioning mode.This paper proposes a new type of composite air-conditioning system,and analyzes the comfort of indoor thermal environment and its influencing factors.The new type of composite air conditioning system is composed of air source heat pump unit+small temperature difference terminal equipment and independent fresh air system.This paper describes the principle and simulation theory of a new type of composite air conditioning system.In order to verify the feasibility and grid independence of the model,The error of the experimental results is compared with the numerical simulation results.The research of this paper is to establish a numerical model for an office of a foreign-funded enterprise R&D center under the meteorological parameters of Changzhou City,and calculate the cooling and heating load on it.Numerical simulation of heating in winter and cooling in summer with the new type of composite air conditioning system and coil+fresh air system is carried out,then comparing the indoor environment comfort under heating and refrigeration conditions of the two systems,The influence of the installation height of the terminal equipment,the fresh air volume,and the position of the return air outlet on the indoor environment comfort of the new composite air conditioning system is studied.The research shows that:in the comparison between the new air-conditioning system and the fan coil+fresh air system,the temperature field distribution can meet the indoor requirements,but in terms of air distribution and comfort,the new composite air-conditioning system is better than the traditional fan coil+fresh air air-conditioning system.in the study of the factors affecting the indoor thermal environment of new air conditioning under heating conditions,the installation height of the terminal equipment increased from 0.1m to 1.6m,the average PMV value of the room rose from 0.002 to 0.24,and the comfort dropped by 23.8%;The average PPD increased from 6.54 to 6.90,and satisfaction dropped by3.6%.Under cooling conditions,the terminal equipment rises from 0.1m to 1.6m,the PMV value of the room drops from 0.54 to 0.35,and the comfort improves by 43%;the average PPD drops from 13.45 to 9.82,and the satisfaction degree increases by 26.3%,Comprehensive cooling and heating conditions,the comfort is best when the installation height is 1.6m in the height range studied in this paper.When meeting the indoor cooling load requirements,adjusting the load of the fresh air has a significant impact on the comfort of the indoor thermal environment.When the fresh air bears the full latent heat load of the indoor,the indoor comfort is higher.When the fresh air volume in the cooling condition is 324m~3/h,the influence of the position of the return air outlet on the indoor air distribution is analyzed.It is found that different return air outlet positions have little effect on the overall airflow organization of the system,and have a small impact on indoor comfort.Among them,indoor comfort is the best under side return air conditions.This research provides a reference for the setting of cooling and heating design parameters of the small temperature difference heat exchange terminal+fresh air composite system,and also adds technical and theoretical experience for the use of the system in public buildings in the South and other places.